documentclass[legalpaper, 12pt, addpoints]{exam}

usepackage{tikz}
usepackage{karnaugh-map}

CorrectChoiceEmphasis{itseriescolor{red}}

begin{document}
begin{questions}

question The following is a 2x4 k-map:

begin{karnaugh-map}[4][2][1][$xy$][$z$]
     maxterms{0,1,4,5}
     manualterms{,,1 (b),1 (a),,, 1 (d), 1 (c)}
end{karnaugh-map}

end{questions}
end{document}